Wasn’t it just the other day that teachers confiscated cellphones and principals warned about oversharing on MySpace?

Now, Erin Olson, an English teacher in Sioux Rapids, Iowa, is among a small but growing cadre of educators trying to exploit Twitter-like technology to enhance classroom discussion. Last Friday, as some of her 11th graders read aloud from a poem called “To the Lady,” which ponders why bystanders do not intervene to stop injustice, others kept up a running commentary on their laptops.

The poet “says that people cried out and tried but nothing was done,” one student typed, her words posted in cyberspace.

“She is giving raw proof,” another student offered, “that we are slaves to our society.”

Instead of being a distraction — an electronic version of note-passing — the chatter echoed and fed into the main discourse, said Mrs. Olson, who monitored the stream and tried to absorb it into the lesson. She and others say social media, once kept outside the school door, can entice students who rarely raise a hand to express themselves via a medium they find as natural as breathing.

“When we have class discussions, I don’t really feel the need to speak up or anything,” said one of her students, Justin Lansink, 17. “When you type something down, it’s a lot easier to say what I feel.”

With Twitter and other microblogging platforms, teachers from elementary schools to universities are setting up what is known as a “backchannel” in their classes. The real-time digital streams allow students to comment, pose questions (answered either by one another or the teacher) and shed inhibitions about voicing opinions. Perhaps most importantly, if they are texting on-task, they are less likely to be texting about something else.

Nicholas Provenzano, an English teacher at Grosse Pointe South High School, outside Detroit, said that in a class of 30, only about 12 usually carried the conversation, but that eight more might pipe up on a backchannel. “Another eight kids entering a discussion is huge,” he noted.

Skeptics — and at this stage they far outnumber enthusiasts — fear introducing backchannels into classrooms will distract students and teachers, and lead to off-topic, inappropriate or even bullying remarks. A national survey released last month found that 2 percent of college faculty members had used Twitter in class, and nearly half thought that doing so would negatively affect learning. When Derek Bruff, a math lecturer and assistant director of the Center for Teaching at Vanderbilt University, suggests fellow professors try backchannels, “Most look at me like I’m coming from another planet,” he said.

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A discussion on Today's Meet from Erin Olson's English Class in Sioux Rapids, Iowa, about a poem called "To the Lady."

“The word on the street about laptops in class,” Dr. Bruff added, is that students use them to tune out, checking e-mail or shopping. He said professors could reduce such activity by giving students something class-related to do on their mobile devices.

Besides Twitter, teachers have turned to other platforms for backchannels, some with more structure and privacy. Most are free on the Web and — so far — free of advertising. Google Moderator lets a class type questions and vote for the ones they would most like answered. Today’s Meet, used by Mrs. Olson, sets up a virtual “room.”

Purdue University, in Indiana, developed its own backchannel system, Hot Seat, two years ago, at a cost of $84,000. It lets students post comments and questions, which can be read on laptops or smartphones or projected on a large screen. Sugato Chakravarty, who lectures about personal finance, pauses to answer those that have been “voted up” by his audience.

Before Hot Seat, “I could never get people to speak up,” Professor Chakravarty said. “Everybody’s intimidated.”

“It’s clear to me,” he added, “that absent this kind of social media interaction, there are things students think about that normally they’d never say.”

But the technology has been slow to win over faculty. It was used in just 12 courses this spring. Sandra Sydnor-Bousso, a professor of hospitality and tourism management, said Hot Seat did not mesh well with her style of walking around class to encourage a dialogue. “The last thing I want to do is to give them yet another way to distract themselves.”

In high schools and elementary schools, teachers try to exercise tight control over backchannels, often reviewing a transcript after class for inappropriate remarks. Even schools that encourage students to use mobile devices prohibit gossip during class.

In Exira, Iowa, Kate Weber uses the technology for short periods almost daily with her fourth graders. “You’d think there’s a lot of distraction, but it’s actually the opposite,” she said. “Kids are much quicker at stuff than we are. They can really multitask. They have hypertext minds.”

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A backchannel discussion about the death of Osama bin Laden.

During a reading lesson, she recalled, a story included the word “queue.” Using a school-issued Macbook, “one student asked, ‘What is a queue?’ ” Mrs. Weber said. “If they’d have read that individually they wouldn’t have been brave enough to raise their hands. They would have just read over it. But another student answered, ‘It’s a ponytail.’ The whole class on the backchannel had an a-ha moment.”

“I am in awe at how independent they’ve become using that as a means of comprehension,” she added.

The 11th graders in Mrs. Olson’s class said the backchannel had widened their appreciation of one another. “Everybody is heard in our class,” said Leah Postman, 17.

Janae Smith, also 17, said, “It’s made me see my peers as more intelligent, seeing their thought process and begin to understand them on a deeper level.”

On Friday, their teacher continued to develop a semester-long theme: how free the individual is in society. Students watched a YouTube video that compares how much humanitarian aid could be bought for the $150,000 cost of a slick music video.

Earlier in the week, students had staged a rally to support American troops in response to picketing they had seen on the news by the fringe Westboro Baptist Church of Kansas at a funeral for an Iowa soldier killed in Afghanistan.

Mrs. Olson asked her students to connect “the argument” of the poem they read and the video with their own rally. As the discussion swirled in class, one student typed on the backchannel: “We tend to have the attitude that someone else will do it. But what happens when everyone thinks the same as you?”

“It only takes one individual to change,” another typed. “If you want something to change you have to be willing to be that voice.”

“It really shows the impact one change can make,” a third student wrote.

“I agree with Katie!” someone added. “This class has given us a voice!”

A version of this article appears in print on May 13, 2011, on Page A1 of the New York edition with the headline: Speaking Up in Class, Silently, Using the Tools of Social Media. Order Reprints|Today's Paper|Subscribe